This invention relates to ramps used to park read-write head sliders in disk drives.
Disk drives are an important data storage technology based on several crucial components including disk media surfaces and read-write heads. When in operation, the rotation of disk media surfaces, with respect to the read-write heads, causes each read-write head to float a small distance off the disk media surface it accesses.
When the disk media surface is not rotating with respect to the read-write head, mechanical vibrations acting upon the disk drive can cause the read-write head to collide with the disk media surface, unless they are separated.
This separation is often referred to as xe2x80x9cparkingxe2x80x9d the read-write heads. Parking the read-write heads minimizes the possibility of damaging the disk media surfaces and/or the read-write heads due to these mechanical collisions. Often such parking mechanisms include a ramp, on which the head slider(s) are xe2x80x9cparkedxe2x80x9d, and a latch mechanism.
When the disk media surfaces are rotating, the read-write head(s) are very close to the disk media and they often pickup traces of the lubricants used in the disk drive. These traces of lubricant degrade the ability of a read-write head to access the disk media surface.
FIG. 1A illustrates a typical prior art high capacity disk drive 10 including actuator arm 30 with voice coil 32, actuator axis 40, suspension or head arms 50-58 with slider/head unit 60 placed among the disks.
FIG. 1B illustrates a typical prior art high capacity disk drive 10 with magnet actuator 20, actuator arm 30 with voice coil 32, actuator axis 40, head arms 50-54 and Head Suspension Assemblies (HSA""s) 60-66 with the disks removed.
Since the 1980xe2x80x2s, high capacity disk drives 10 have used voice coil actuators 20-66 to position their read/write heads over specific tracks. The heads are mounted on head sliders at the far end of HSA""s 60-66 from the voice coil 32. The heads float a small distance off the disk drive surface 12 when in operation. Often there is one head slider for a given disk drive surface. There are usually multiple heads in a single disk drive, but for economic reasons, usually only one voice coil actuator.
Voice coil actuators are further composed of a fixed magnet actuator 20 interacting with a time varying electromagnetic field induced by voice coil 32 to provide a lever action via actuator axis 40. The lever action acts to move head arms 50-54 positioning head slider units 60-66 over specific tracks with remarkable speed and accuracy. Actuator arms 30 are often considered to include voice coil 32, actuator axis 40, head arms 50-54 and HSA""s 60-66. Note that actuator arms 30 may have as few as a single head arm 50. Note also that a single head arm 52 may connect with two HSAs 62 and 64.
FIG. 2A illustrates a Contact Start Stop (CSS) actuator arm 30 of the prior art.
A magnet is affixed to the tail end of the voice coil 32 region, which when near a second magnet located in either the top yoke or bottom yolk of the fixed magnet region 20, will tend to attract actuator 30 to a parking site often inside the disk media. Magnetic latches are used with CSS designs.
The outside disk surface approach to parking read-write heads parks the read-write head or heads on a ramp outside the disk surface, removing and/or minimizing the possibility for contact when the disk is not in operation.
Read-write heads must be positioned very accurately over the track in the disk media surface they are to access. Errors in this activity are known as track positioning errors, triggering a Position Error Signal (PES).
For a CSS drive, the lubricant pickup by the read-write head(s) during the track seeking process results in a phenomena known as xe2x80x9cflying stictionxe2x80x9d. Flying stiction may lead to experiencing a high stiction force at the mechanical interface of the read-write head and the disk media surface. The high stiction force at the mechanical interface between the read-write head and the disk media surface may lead to track positioning errors.
FIG. 2B illustrates an actuator arm 30 including head suspension assembly 60 with head slider 90 on ramp 100 for a parking mechanism outside the disk media surface 12 (not shown), as found in the prior art.
FIG. 3 illustrates a prior art loading ramp 100 engaging lifting tab 92 coupled with head slider 90 by a head suspension assembly 60 positioning the read-write head of head slider 90 in a parking zone with lifting tab 92 engaging loading ramp 100 in region 104.
To park the read-write head, the head suspension assembly 60 moves from the left, with lifting tab 92 engaging the loading ramp at engagement region 102 and proceeding to region 104. This places the read-write head 90 into its parking zone.
Block 106 acts to limit lifting tab 92 and, therefore, the read-write head of slider 90, from moving upward, while region 104 acts to limit lifting tab 92 and the read-write head of slider 90 from moving downward. The rising sections on either side of region 104 further act to limit accidental movement of lifting tab 92 and the coupled head slider 90 in the horizontal directions.
Region 108 of loading ramp 100 is often used during the assembly of a disk drive in a fashion similar to engagement region 102. Movement of lifting tab 92 is from the right engaging loading ramp 100 at 108 and proceeding to region 104 to park the read-write head.
For a ramp loading disk drive, the read-write head(s) do not rest on the media 12 during the start and stop operations of the disk drive. A central advantage to such disk drives is improved mechanical shock resistance. Improved shock resistance increases the durability and life expectancy of the disk drive.
However, ramp-loading disk drives also present some new problems. Any lubricant that is picked up by the read-write head is more likely to stay on the read-write head, rather than get smeared on the disk media.
Lubricants migrate due to disk rotation onto the disk media surface. After a time, some of the migrated lubricant enters the mechanical interface between the read-write head and the disk media surface, making contact, and sticking to the read-write head. When this occurs, the read-write head tends to stick to the disk media surface, which is known as lubricant stiction. Lubricant stiction is a known cause of track positioning errors. In extreme cases, lubricant stiction acts as a glue between the read-write head and the disk media surface, preventing the disk media surface from rotating at the proper speed. Sometimes the disk media surface cannot rotate at all.
Lubricant stiction is likely to become more pronounced as the flying height of the read-write heads over the disk media surface decreases. Therefore, track positioning errors from lubricant stiction are likely to increase as the flying height decreases.
To summarize, what is needed is a method and/or apparatus removing at least some of the lubricant picked up by a read-write head for a ramp loading disk drive.
The invention solves at least all the problems discussed for ramp loading disk drives.
The invention includes a method of wiping a read-write head on a ramp including the following. Loading the read-write head into a parking region based upon the lifting tab engaging the loading ramp. Wiping the read-write head on a wiping part of the loading ramp when the lifting tab engages the loading ramp and when the read-write head is outside in the parking region. Note that the wiping part is a convex finger crossing the read-write head path of motion with respect to the lifting tab engagably moving across the loading ramp.
The invention includes a loading ramp for a read-write head coupled to a lifting tab by a head suspension assembly. The loading ramp includes the following. A lifting tab path for engaging the lifting tab to create a motion path for the read-write head based upon the lifting tab engagably moving along the lifting tab path. A convex finger contacting the motion path of the read-write head provides a wiping of the read-write head. Note that the motion path for the read-write head includes a parking region and the convex finger contacts the motion path outside the parking region.
When the read-write head is at least partially covered with a lubricant drop providing a lubricant drop surface, the convex finger contacting the motion path of the read-write head comes within a distance of the read-write head motion path. The convex finger, by approaching close to the read-write head motion path, breaks the lubricant drop surface, providing the wiping of the read-write head.
The invention also includes disk drives containing the loading ramp and the head suspension assembly.
Note that the loading ramp 2002 may be located outside the disk media surface or inside the disk media surface. When a disk drive contains more than one disk media surface, the loading ramp is preferably located outside the disk media surface. However, when the disk drive contains one disk media surface, it may be preferable to locate the loading ramp inside the disk media surface.
Locating the loading ramp inside the disk media surface refers to positioning the loading ramp over the disk media surface. This alternative to CSS disk drive parking has the advantage of greater mechanical shock resistance without the problem of lubricant buildup.
Note that the convex fingers are approximately convex. The convex fingers may approximate an elliptical cylinder, ellipsoid, paraboloid, cylinder, or hemisphere in different embodiments of the invention.
These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings.